Macro Lens- What Is This?

[paulh428]

Sorry, new to this but I have a Tamron AF XR Di 28-300 mm Macro lens on a Canon Rebel XT. I try to gain that shallow depth of field for things like portrait or up close pictures for food, etc but always end up getting the background focused and foreground blurred instead of vice versa. What's am I doing wrong?

Camera: DSLR: Canon Rebel XT

[PhotoNewt]

Originally Posted by paulh428

Sorry, new to this but I have a Tamron AF XR Di 28-300 mm Macro lens on a Canon Rebel XT. I try to gain that shallow depth of field for things like portrait or up close pictures for food, etc but always end up getting the background focused and foreground blurred instead of vice versa. What's am I doing wrong?

Camera: DSLR: Canon Rebel XT

Hello Paul.

Depth of field (DoF) control in creative photography is dependent additional factors besides the len you choose. I believe your lens has a minimum aperture that goes from f/3.5 on the short end, to f/6.3 on the long end. Aperture is a major determinant of DoF, the larger the aperture (smaller f/number), the shallower your DoF will be given every other variables remain constant. So to get shallow DoF, you need to use the largest aperture available (there are other considerations regarding image quality you need to be aware of when using a consumer-grade lens wide open).

The other DoF variable you can control with your lens is the focal length. When all other variables remain constant, a longer focal length (i.e., 300mm) will blur the background more than a wide angle setting (i.e., 28mm). So using the longest focal length possible will afford more blurring of the background - in your lens however, this may be partially offset by the smaller maximum aperture as you zoom to the long end (towards the 300mm side).

Outside of your lens there are a couple of additional variables you can manipulate to get shallower DoF. The closer your subject is to your lens, the shallower your DoF will become. In addition, the more distance between the subject and the background, the more out-of-focus the background will appear.

The next time you try you can use all these to obtain a shallower DoF:

1. Zoom your lens to about 200mm.
2. Set your camera's exposure control to [Av] and select the largest aperture possible (smallest f/number, such as 3.5 to 5.6).
3. Position your main subject as far away from the background as possible.
4. Frame your subject as close to the lens as possible.
5. Set your lens on Manual focus and focus through the eye piece so you can have maximum control of the focal plane - you can also select the center auto focus point and use this one so you control where your camera is focusing.

With this setup is better to mount your camera on a tripod, enable the mirror lock function (using the custom function menu) and use the camera's self-timer mode to take the picture - this will minimize camera shake and provide sharper pictures.

Hope this helps.